Cricothyroid Muscle Dysfunction Affects Aerodynamic Performance in Patients with Unilateral Vocal Fold Paralysis

BACKGROUND

Emerging evidence has revealed that cricothyroid (CT) muscle dysfunction in unilateral vocal fold paralysis (UVFP) further impairs patients' voices. Given that CT muscle dysfunction does not influence vocal fold position, the mechanism of voice dysfunction induced by dysfunction of CT muscle in UVFP patients remains controversial. This study compares aerodynamics between UVFP patients with and without CT muscle involvement.

METHODS

This cross-sectional study recruited patients with UVFP manifesting dysphonia, and UVFP was confirmed with videolaryngoscopy and laryngeal electromyography (LEMG). Voice analysis and aerodynamic tests were further performed. Patients with (CT+ group) and without (CT- group) CT muscle involvement were compared.

RESULT

A total of 175 patients (40 in the CT+ group and 135 in the CT- group) with UVFP were analyzed. The CT+ group showed lower maximal sound pressure level (SPL) (P=0.039), mean SPL (P=0.042), peak air pressure (P<0.001), mean peak air pressure (P<0.001) and aerodynamic power (P=0.004) than the CT- group.

CONCLUSION

The decrease in SPL, peak air pressure, and aerodynamic power in UVFP patients with CT muscle dysfunction suggests that the effect of CT muscle dysfunction is mediated by a change in aerodynamics.

A Radiotherapy Dose Map-Guided Deep Learning Method for Predicting Pathological Complete Response in Esophageal Cancer Patients after Neoadjuvant Chemoradiotherapy Followed by Surgery

Esophageal cancer is a deadly disease, and neoadjuvant chemoradiotherapy can improve patient survival, particularly for patients achieving a pathological complete response (ypCR). However, existing imaging methods struggle to accurately predict ypCR. This study explores computer-aided detection methods, considering both imaging data and radiotherapy dose variations to enhance prediction accuracy. It involved patients with node-positive esophageal squamous cell carcinoma undergoing neoadjuvant chemoradiotherapy and surgery, with data collected from 2014 to 2017, randomly split into five subsets for 5-fold cross-validation. The algorithm DCRNet, an advanced version of OCRNet, integrates RT dose distribution into dose contextual representations (DCR), combining dose and pixel representation with ten soft regions. Among the 80 enrolled patients (mean age 55.68 years, primarily male, with stage III disease and middle-part lesions), the ypCR rate was 28.75%, showing no significant demographic or disease differences between the ypCR and non-ypCR groups. Among the three summarization methods, the maximum value across the CTV method produced the best results with an AUC of 0.928. The HRNetV2p model with DCR performed the best among the four backbone models tested, with an AUC of 0.928 (95% CI, 0.884-0.972) based on 5-fold cross-validation, showing significant improvement compared to other models. This underscores DCR-equipped models' superior AUC outcomes. The study highlights the potential of dose-guided deep learning in ypCR prediction, necessitating larger, multicenter studies to validate the results.

Pathophysiological Mechanisms Underlying Unilateral Vocal Fold Paralysis in Female Patients: An Ultrasonographic Study

OBJECTIVES

Laryngeal ultrasonography (LUS) has been suggested as an alternative diagnostic tool for unilateral vocal fold paralysis (UVFP). The present study applied LUS and quantitative laryngeal electromyography (LEMG) in female UVFP patients to investigate the pathophysiologic mechanisms of UVFP.

METHODS

In this cross-sectional study, vocal fold (VF) length parameters included resting and phonating VF length measured using B-mode LUS, and color Doppler vibrating length (CDVL) measured using the color Doppler mode.

RESULTS

Forty female patients with UVFP were enrolled, among whom 11 and 29 were assigned to the thyroarytenoid (TA) muscle+cricothyroid (CT) muscle group (with CT involvement) and the TA (without CT involvement) group, respectively. In the TA group, the turn frequency in thyroarytenoid-lateral cricoarytenoid (TA-LCA) on the paralyzed side, as observed through LEMG, correlated with the VF length during the resting phase (R=0.368, P=0.050) and CDVL values (R=0.627, P=0.000) on the paralyzed side. In the TA+CT group, the turn ratio in the CT muscle correlated with the normalized phonatory vocal length change (nPLC; R=0.621, P=0.041) on the paralyzed side.

CONCLUSION

CDVL and nPLC are two parameters that can be utilized to predict the turn frequencies of TA-LCA in UVFP cases without CT involvement, and the turn ratio of CT in cases of UVFP with CT involvement, respectively. The findings suggest that LUS, as a noninvasive tool, can serve as an alternative method for assessing the severity of laryngeal nerve injury and offer valuable insights into the pathophysiology of UVFP.

Non-meningeal, non-pulmonary cryptococcosis with limited posterior uveitis in a kidney organ transplant recipient with antibody-mediated rejection: a case report

BACKGROUND

Cryptococcosis is one of the most frequent fungal eye infections in patients with immunosuppression. Currently, treatment approaches for non-meningeal, non-pulmonary cryptococcosis are based on those used for cryptococcal meningitis or pneumonia.

CASE PRESENTATION

We present a rare case of non-meningeal, non-pulmonary cryptococcosis with clinical manifestations limited to one eye of a cadaveric kidney transplant recipient with chronic-active antibody-mediated rejection. Typical manifestations, diagnosis, and treatments, including antifungal therapies, adjunctive therapies, and immunosuppression reduction, are discussed. After timely diagnosis and treatment, her visual acuity recovered to baseline without recurrence or sequelae of cryptococcosis.

CONCLUSIONS

Clinicians should be aware of rare presentations of fungal infections, especially when a kidney transplant recipient with rejection has been treated with intensive immunosuppressants. Early diagnosis with individualized therapies may have a favorable prognosis.

Wireless, Soft Sensors of Skin Hydration with Designs Optimized for Rapid, Accurate Diagnostics of Dermatological Health

Accurate measurements of skin hydration are of great interest to dermatological science and clinical practice. This parameter serves as a relevant surrogate of skin barrier function, a key representative benchmark for overall skin health. The skin hydration sensor (SHS) is a soft, skin-interfaced wireless system that exploits a thermal measurement method, as an alternative to conventional impedance-based hand-held probes. This study presents multiple strategies for maximizing the sensitivity and reliability of this previously reported SHS platform. An in-depth analysis of the thermal physics of the measurement process serves as the basis for structural optimizations of the electronics and the interface to the skin. Additional engineering advances eliminate variabilities associated with manual use of the device and with protocols for the measurement. The cumulative effect is an improvement in sensitivity by 135% and in repeatability by 36% over previously reported results. Pilot trials on more than 200 patients in a dermatology clinic validate the practical utility of the sensor for fast, reliable measurements.

Palatal hybrid surgery for obstructive sleep apnea-state-of-the-art annotation of uvulopalatopharyngoplasty

BACKGROUND

Surgery for obstructive sleep apnea (OSA) has changed in concept and technique that transformed from radical excision to functional reconstruction. The aim of this study was to investigate the safety and effectiveness of palatal hybrid surgery in OSA patients.

METHODS

Palatal hybrid surgery is a tissue-specific technique (mucosa-preservation, tonsil-excision, fat-ablation, muscle-relocation/suspension) used in treating OSA patients with velopharyngeal obstruction. The study included 46 consecutive adults OSA patients. The palatal hybrid surgery annotates uvulopalatopharyngoplasty in stereoscopic reconstruction of tonsillar fossa (pharyngoplasty), omni-suspension of the soft palate (palatoplasty) and advancement of uvula (uvuloplasty).

RESULTS

No patient experienced airway compromise, voice change or persistent nasal regurgitation following palatal hybrid surgery. One patient existed postoperative tonsillar fossa bleeding received conservative treatment. Postoperative pain in visual analogue scale (VAS) showed average score of 3, 3, 2, 0 at the 1st, 3rd, 7th, 14th day, respectively. Perioperative snoring severity (VAS) (8.7 vs 2.6) and daytime sleepiness (Epworth Sleepiness Scale) (11.3 vs 5.5) all improved significantly (p < 0.001). Posterior air space in retropalatal area increased from 8.4 to 11.1 mm (p < 0.001). Home sleep test showed that apnea-hypopnea index significantly reduced from 41.8 to 18.2 event/h and minimal oxygen saturation increased from 72.4 to 81.5% (p < 0.001). The success rate in individual Friedman stage was 100% (stage I), 63% (stage II) and 58% (stage III) with a total success rate of 63%.

CONCLUSION

Palatal hybrid surgery using tissue-specific maneuver annotates UPPP in concept and technique. The results show that palatal hybrid surgery is mini-invasive with low morbid and is effective in improving subjective clinic symptoms, objective sleep parameters and success rate of OSA.

Volumetric Changes after Coblation Ablation Tongue (CAT) in Obstructive Sleep Apnea Patients

Background: Obstruction of the tongue is commonly seen in patients with obstructive sleep apnea (OSA). This study proposed whole tongue treatment using coblation ablation tongue (CAT) and aimed to explore the potential association between the dimensions of a tongue and the severity of OSA, to inspect volumetric changes of the tongue after CAT, and to search for factors that influence outcome of tongue volume change. Methods: The prospective study enrolled 12 OSA patients (all male, average age: 35 years, average apnea/hypopnea index (AHI): 45.5 event/h, average body mass index (BMI): 27.0 kg/m²). All patients received multi-level sleep surgery including septomeatoplasty, uvulopalatopharyngoplasty, and CAT. The CAT used a coblation wand to perform uniform multiple ablations (15 points, body −6, base −9) on dorsal tongue. Three dimensions of the tongue (length, height, and width) and tongue volume were measured from head and neck computed tomography. The perioperative changes in the tongue dimension/volume and AHI were assessed at baseline and 3 months after surgery. Result: The baseline tongue length and AHI had a significant correlation (r = 0.60, p = 0.02). The multi-level surgery significantly improved AHI (43.8 vs. 23.7, p = 0.008). The CAT significantly decreased tongue volume from 91.3 to 85.6 cm³ (p = 0.02), with an average tongue volume reduction of 5.7 cm³ per person and 0.38 cm³ per ablation. Further outcome analysis showed surgical success was significantly higher in patients with non-hypertrophic lingual tonsils (grade I/II) than in those with hypertrophic lingual tonsils (grade III/IV) (p = 0.02). Conclusion: Length of the tongue is associated with the severity of OSA. The CAT significantly decreased the tongue volume in OSA patients. A volumetric reduction of 0.38 cm³ per ablation could be useful in the optimal reduction of tongue for OSA. The CAT significantly enlarged the retroglossal airway volume, which is related to the non-hypertrophic lingual tonsil.

Comprehensive Evaluation of Vocal Outcomes and Quality of Life after Total Laryngectomy and Voice Restoration with J-Flap and Tracheoesophageal Puncture

Simple Summary

Laryngopharyngectomy is still the treatment of choice in locally advanced pharyngolaryngeal tumors not eligible for organ preservation protocols. Loss of speech capacity has been reported as one of the factors that most affect the patient-reported quality of life. Thus, the reconstructive goals are restoring the pharynx and possibly the voice in such a scenario. For decades, tracheoesophageal puncture (TEP) has allowed proper voice rehabilitation; however, TEP has a non-neglectable financial expenditure and complication rate. Therefore, we recently reported a novel flap design and surgical technique that shares the same principles of TEP, without the need to change any device over time, named J-flap. This study aimed to analyze both techniques’ subjective and objective vocal outcomes and their impact on overall and voice-related quality of life.

Abstract

Background: Tracheoesophageal puncture with a voice prosthesis is the gold standard for speech rehabilitation in patients that receive a laryngopharyngectomy. However, a novel surgical technique, using a tubularized anterolateral tight flap, named “J-flap,” has been demonstrated to produce adequate voice restoration. We aimed to compare the outcomes and the quality of life of patients who underwent voice rehabilitation with both techniques. Methods: We enrolled patients that underwent laryngopharyngectomy and voice restoration surgery. The control group received a tracheoesophageal puncture with a voice prosthesis, while the study group received J-flap reconstruction. A total of 20 patients received voice prosthesis rehabilitation, while 18 received J-flap reconstruction. Speech and vocal outcomes and quality of life metrics were collected. Results: The objective phonatory performances and the acoustic voice analysis did not outline a significant difference. Speech pathologists judged the consonant pronunciation in the J-flap group as less accurate (p < 0.001). The voice handicap index revealed a moderate impairment for the J-flap group (p < 0.001). Quality of life scores were higher for the voice prosthesis group. Conclusion: Voice prostheses and J-flaps share similar objective phonatory outcomes. Quality of life was more impaired in the J-flap group. In our view, these two techniques possess complementary characteristics in clinical practice, taking into account health care system regulations and patients’ social background.

Carcinoma Showing Thymus-like Differentiation (CASTLE) with Synchronous Papillary Thyroid Carcinoma: A Case Report and Review

Carcinoma showing thymus-like differentiation (CASTLE) is a rare malignant tumor that accounts for 0.1%-0.15% of all thyroid cancers. More than half of the patients have tumor extension to adjacent organs, including the recurrent laryngeal nerve, trachea, and esophagus. The diagnosis of CASTLE is based on histology and immunohistochemistry. A 58-year-old female patient complained of hoarseness for one and half years. Right side vocal cord palsy was diagnosed by fiberscopy. Thyroid sonography revealed right thyroid tumors, which were reported to be papillary thyroid carcinoma through FNAC. Total thyroidectomy with central lymph node dissection was performed. Pathologist found 2 isolated malignancy tumors. One patient in the right thyroid lobe had papillary thyroid carcinoma features. The other extrathyroid tumor seemed to be separated from the first tumor and invaded the thyroid capsule. After multiple immunohistochemical studies, PTC synchronous CASTLE was the final diagnosis. Coexisting PTC and CASTLE is very rare. This is the first report to describe a case showing PTC at first, while subsequent pathologic examination revealed the presence of CASTLE in addition to PTC. Since the prognosis of CASTLE is favorable, the treatment is different from other aggressive thyroid cancers, such as poorly differentiated or anaplastic thyroid carcinoma.

[A Preliminary Study to Investigate Frailty in Advanced Lung Cancer Patients Before Receiving Immunotherapy]

BACKGROUND

Most advanced lung cancer patients have already received many types of treatment before starting immunotherapy. Compared with advanced lung cancer patients under first-line treatment, those receiving immunotherapy are vulnerable to many health problems and increased frailty.

PURPOSE

This study was designed to investigate frailty in advanced lung cancer patients before starting immunotherapy.

METHODS

A total of 52 pre-immunotherapy patients completed the survey. Frailty status was determined using the Fried standard and survey questionnaires included the Barthel Index, Center for Epidemiologic Studies Depression Scale, the Chinese version of scales of international physical activities questionnaire (short version). In addition, the handgrip and 4.6-meter walk speed of the participants were measured.

RESULTS

The ratio of frailty was 17.3%, with comorbidities (p = .023), body mass index (p = .004), Eastern Cooperative Oncology Group Status (p < .001), activities of daily living status (p < .001), albumin (p = .042), and C-reactive protein (p = .048) all associated with frailty.

CONCLUSIONS / IMPLICATIONS FOR PRACTICE

In this study, weight loss and low physical activity were the main symptoms of frailty in patients with advanced lung cancer. Therefore, healthcare workers should assess the nutrition and physical activity status of patients before initiating immunotherapy. We suggest that clinical care workers provide frailty care to patients before administering immunotherapy.

Speech Performance after Anterolateral Thigh Phonatory Tube Reconstruction for Total Laryngectomy

OBJECTIVE

Traditionally, after total laryngopharyngectomy (TLP), patients cannot speak without a prosthesis or an artificial larynx. In Taiwan, most patients use a commercialized pneumatic laryngeal device (PLD). Phonatory tube reconstruction with the anterolateral thigh (ALT) flap is a novel, modified version of synchronous digestive and phonatory reconstruction involving a free muscular cutaneous flap. This study reviewed and compared speech performance between patients who underwent novel flap reconstruction and conventional PLD users.

METHOD

We retrospectively reviewed patients with laryngeal or hypopharyngeal cancer who underwent TLP from August 2017 to September 2019. The voice handicap index (VHI), speech intelligibility, acoustic and aerodynamic analysis results, and speech range profile (SRP) were compared between patients who underwent ALT phonatory tube reconstruction (ALT group) and those using PLDs (PLD group).

RESULTS

Twenty patients were included; 13 patients were included in the ALT group, and 7 patients were included in the PLD group. Compared to the PLD group, the ALT group had a better fundamental frequency range (P < .001) and semitone range (P < .001) during speech but showed worse jitter, shimmer, and harmonic-to-noise ratios. The two groups showed comparable VHI and speech intelligibility performance.

CONCLUSIONS

The ALT phonatory tube, a novel flap for reconstruction, can restore digestive and voice functions simultaneously. Compared with PLD use, ALT phonatory tube reconstruction yields an improved speech range and comparable levels of voice handicap and speech intelligibility, suggesting that the technique is a good alternative for patients after TLP.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:1349-1357, 2021.

Two trajectories of functional recovery in thyroid surgery related unilateral vocal cord paralysis

BACKGROUND

Iatrogenic unilateral vocal fold paralysis caused by thyroid surgery induces profound physical and psychosocial distress in patients. The natural course of functional recovery over time differs substantially across subjects, but the mechanisms underlying this difference remain unclear. In this study, we examined whether the anatomic site of the lesion affected the trajectory of recovery.

METHODS

In this prospective case series study in a single medical center, patients with thyroid surgery-related unilateral vocal fold paralysis were evaluated using quantitative laryngeal electromyography, videolaryngostroboscopy, voice acoustic analysis, the Voice Outcome Survey, and the Short Form-36 quality-of-life questionnaire. Patients with and without superior laryngeal nerve injuries were compared.

RESULTS

Forty-two patients were recruited, among whom 15 and 27 were assigned to the with and without superior laryngeal nerve injury groups, respectively. Compared with the group without superior laryngeal nerve injury, the group with superior laryngeal nerve injury group demonstrated less improvement in the recruitment of vocal fold adductors, and the group also had more severe impairment of vocal fold vibration, maximum phonation time, jitter, shimmer, and harmony-to-noise ratio at the first evaluation. This difference was also found in the glottal gap and maximum phonation time 12 months after the injury.

CONCLUSION

Among patients with thyroid surgery-related unilateral vocal fold paralysis, superior laryngeal nerve injury induces a distinctively different recovery trajectory compared with those without superior laryngeal nerve injury characterized by less reinnervation of vocal fold adductors and worse presentation in terms of the glottal gap and maximum phonation time. This study emphasizes the importance of superior laryngeal nerve function and its preservation in thyroid surgery.

Parapharyngeal fat pad area at the subglosso-supraglottic level is associated with corresponding lateral wall collapse and apnea-hypopnea index in patients with obstructive sleep apnea: a pilot study

The aim of this study was to assess associations between fat pad areas at various anatomic levels and the sites of lateral wall collapse and disease severity in adult patients with obstructive sleep apnea (OSA). Forty-one patients with OSA who prospectively underwent drug-induced sleep computed tomography were included. Areas of parapharyngeal fat pads and degrees of lateral wall collapse at three representative anatomic levels (nasopharynx, oropharynx, and subglosso-supraglottis), and apnea-hypopnea index (AHI) were measured. In the subglosso-supraglottic region, the parapharyngeal fat pad area in 17 (41%) patients with complete lateral wall collapse was significantly larger than that in 24 (59%) patients without complete collapse (median, 236.0 mm² vs 153.0 mm²; P = 0.02). In multivariate regression analysis, the parapharyngeal fat pad area at the subglosso-supraglottic level (β = 0.02; P = 0.01) and body mass index (β = 3.24; P = 0.01) were independently associated with AHI. Our preliminary results supported that parapharyngeal fat pads at the subglosso-supraglottic level may be involved in the development of lateral wall collapse and then determine the severity of OSA. Further studies are warranted to investigate the effect of reducing parapharyngeal fat pads in the treatment of OSA.

Intrapharyngeal surgery with integrated treatment for obstructive sleep apnea

Obstructive sleep apnea (OSA) is a common disease in adults, which influences human relations, quality of life and associates with major complications. Continuous positive airway pressure (CPAP) is the gold standard treatment modality in OSA patients. For patients incompliant or unwilling to CPAP therapy, surgery is an alternative treatment. Sleep surgery for OSA include intrapharyngeal surgery, extrapharyngeal surgery and bariatric surgery addressing upper airway soft tissue, maxillofacial bone, and obesity, respectively. Among sleep surgeries, intrapharyngeal surgery (soft tissue surgery) is widespread used and serves overwhelming majority in OSA surgical patients. Despite the popularity of intrapharyngeal surgery, its outcomes can be influenced by multiple factors and consequently need conjunctive remedy to enhance at the short-term and sustain in the long-term. In this article, we introduce updated indications for treating OSA, practical principle in decision-making between CPAP and surgery, hybrid procedures in treating obstruction at the nose, palate, tongue and epiglottis, and postoperative integrated treatment including oropharyngeal myofunctional therapy (local), positional therapy (regional), and body weight reduction (systemic), and circadian rhythm (central). In summary, intrapharyngeal surgery is a target-oriented procedure that needs to be performed precisely and combines with integrated treatment as a holistic care for OSA patients.

Risk factors for poor outcomes of children with acute acalculous cholecystitis

BACKGROUND

Acute acalculous cholecystitis (AAC) is generally considered to be a mild disease in children; however, if left untreated or treated without caution, AAC can lead to severe outcomes, such as death. The objectives of this study were to present the clinical features and identify the predictors of mortality in pediatric AAC.

METHODS

Patients diagnosed with AAC between 2005 and 2012 were enrolled. AAC was defined by the presence of fever and an echo-proven thickened gallbladder wall exceeding 4 mm. A poor health outcome was defined as death. Further information related to the demographics, clinical manifestations, laboratory results, ultrasound findings, and pathogens present in the AAC patients was also collected. Predictors of mortality were identified by association analyses and confirmed by multivariate logistic regression.

RESULTS

A total of 147 pediatric AAC patients (male/female = 1.01, mean age = 5.2 years) were included in this retrospective study. The most common clinical presentation was an elevated C-reactive protein level (84%) followed by hepatomegaly (80%) and anorexia (78%). AAC in children was associated with various diseases, including infectious diseases (70%), systemic diseases (13%), and malignancy (11%). Fourteen of the 147 (9.25%) patients died during the study period. The presences of thrombocytopenia, anemia, gallbladder sludge, hepatitis, and/or sepsis plus hepatitis were found to be the important predictors of AAC mortality.

CONCLUSIONS

The factors associated with AAC mortality were anemia, thrombocytopenia, gallbladder sludge, hepatitis, and sepsis plus hepatitis. These predictors are likely to help clinicians identify patients who are at a high risk of poor prognoses and make appropriate clinical decisions.

Hemodynamic stability during laryngeal electromyography procedures

BACKGROUND

Laryngeal electromyography (LEMG) is accepted as safe, with minimal side effects. However, patient hemodynamic stability, during these procedures, has not been reported. This study aimed to investigate the hemodynamics in patients undergoing LEMG and determine the risk factors for hemodynamic changes.

METHODS

We recruited 89 consecutive patients who underwent LEMG. Baseline and postprocedural changes in vital signs were analyzed.

RESULTS

Diastolic blood pressure (DBP) increased from 75.08 ± 11.54 mmHg preprocedure to 77.4 ± 11.91 mmHg postprocedure (p = .006); pulse rate (PR) increased from 78.1 ± 13.3 beats per minute preprocedure to 80.02 ± 13.69 postprocedure (p = .027). Systolic blood pressure (SBP) and oxygen saturation were unchanged after the procedure. However, about 17% of patients experienced profound changes in vital signs of >20% above baseline during LEMG. The hemodynamic changes did not differ between sexes or between surgical and non-surgical etiologies of vocal fold paralysis. Two patients experienced profound but reversible near-syncope during the procedure.

CONCLUSIONS

LEMG is a safe procedure with few immediate complications, though it may affect the patient's hemodynamic status by increasing DBP and PR. The hemodynamic monitoring is recommended so that timely intervention can be applied in case any warning sign occurs.

Peptide Ligation by a Reversible and Reusable C-Terminal Thiol Handle

[reaction: see text] Peptide ligation of noncysteinyl residues can be achieved conveniently by a reversible C-terminal thiol handle together with a Ag(+) ion-assisted S,N-acyl migration. The regenerated C-terminal handle permits tandem ligation of multiple segment.

RT-PCR detection of the expression of the polymerase gene of a novel reptilian herpesvirus in tumor tissues of green turtles with fibropapilloma

An alpha-herpesvirus has recently been associated with green turtle fibropapilloma (FP). To further understand the etiological role of this newfound green turtle herpesvirus (GTHV) in the pathogenesis of FP, expression of GTHV polymerase ( pol) gene was determined in tumors and normal-appearing nontumor tissues and organs from five green turtles suffering multiple fibropapillomas, using reverse transcription-polymerase chain reaction (RT-PCR). Amplification of RNA prepared from tumor tissues evidenced the substantial expression of GTHV DNA pol gene in all specimens tested (15/15). However, GTHV pol gene expression in normal-appearing tissues and organs of affected animals was limited (4/45), and GTHV mRNA was detected only in periorbital tissue (1/2), gall bladder (2/5) and lung (1/5) by nested RT-PCR. By contrast, RT-PCR evaluation of RNA isolated from non-tumored turtles revealed undetectable expression of this herpesvirus gene. cDNA sequence analysis revealed that GTHV gene sequences were identical in different tumors. Our data represent the first evidence of the replication of this putative turtle herpesvirus in affected green turtles and fibropapilloma tissues are always active sites of GTHV mRNA synthesis. These findings extend and substantiate the pathogenic association of GTHV with FP.

Correlations of cationic charges with salt sensitivity and microbial specificity of cystine-stabilized beta -strand antimicrobial peptides

The electrostatic interaction of the charge cluster of an amphipathic peptide antibiotic with microbial membranes is a salt-sensitive step that often determines organism specificity. We have examined the correlation between charge clusters and salt insensitivity and microbial specificity in linear, cyclic, and retro-isomeric cystine-stabilized beta-strand (CSbeta) tachyplesin (TP) in a panel of 10 test organisms. Cyclic tachyplesins consisting of 14 and 18 amino acids are constrained by an end-to-end peptide backbone and two or three disulfide bonds to cross-brace the anti-parallel beta-strand that approximates a "beta-tile" structure. Circular dichroism measurements of beta-tile TPs showed that they displayed ordered structures. Control peptides containing the same number of basic amino acids as TP but lacking disulfide constraints were highly salt sensitive. Cyclic TP analogues with six cationic charges were more broadly active and salt-insensitive than those with fewer cationic charges. Reducing their proximity or number of cationic charges, particularly those with three or fewer basic amino acids, led to a significant decrease in potency and salt insensitivity, but an increased selectivity to certain Gram-positive bacteria. An end-group effect of the dibasic N-terminal Lys of TP in the open-chain TP and its retroisomer was observed in certain Gram-negative bacteria under high-salt conditions, an effect that was not found in the cyclic analogs. These results suggest that a stable folded structure together with three or more basic amino acids closely packed in a charged region in CSbeta peptides is important for salt insensitivity and organism specificity.

Antimicrobial dendrimeric peptides

Dendrimeric peptides selective for microbial surfaces have been developed to achieve broad antimicrobial activity and low hemolytic activity to human erythrocytes. The dendrimeric core is an asymmetric lysine branching tethered with two to eight copies of a tetrapeptide (R4) or an octapeptide (R8). The R4 tetrapeptide (RLYR) contains a putative microbial surface recognition BHHB motif (B = basic, H = hydrophobic amino acid) found in protegrins and tachyplesins whereas the octapeptide R8 (RLYRKVYG) consists of an R4 and a degenerated R4 repeat. Antimicrobial assays against 10 organisms in high- and low-salt conditions showed that the R4 and R8 monomers as well as their divalent dendrimers contain no to low activity. In contrast, the tetra- and octavalent R4 and R8 dendrimers are broadly active under either conditions, exhibiting relatively similar potency with minimal inhibition concentrations < 1 microm against both bacteria and fungi. Based on their size and charge similarities, the potency and activity spectrum of the tetravalent R4 dendrimer are comparable to protegrins and tachyplesins, a family of potent antimicrobials containing 17-19 residues. Compared with a series of linearly repeating R4 peptides, the R4 dendrimers show comparable antimicrobial potency, but are more aqueous soluble, more stable to proteolysis, less toxic to human cells and more easily synthesized chemically. These results suggest repeating peptides that cluster the charge and hydrophobic residues may represent a primitive form of microbial pattern-recognition. Incorporating such knowledge in a dendrimeric design therefore presents an attractive approach for developing novel peptide antibiotics.

Tandem peptide ligation for synthetic and natural biologicals

We describe the concept and methods of peptide ligation and tandem peptide ligation for preparing synthetic and natural biologicals. Peptide ligation is a segment coupling method for free peptides or proteins through an amide bond without the use of a coupling reagent or a protecting group scheme. Because unprotected peptides or proteins prepared from either a chemical or biochemical source are being used as building blocks, the ligation removes the size limitation for peptide and protein synthesis. A key feature of the peptide ligation is that the coupling reaction is orthogonal, i.e. it is specific to a particular alpha-amino terminus (NT). This NT-amino acid-specific feature permits the development of a tandem peptide ligation method employing three unprotected peptide segments containing different NT-amino acids to form consecutively two amide bonds, an Xaa-SPro (thiaproline) and then an Xaa-Cys. This strategy was tested in peptides ranging from 28 to 70 amino acid residues, including analogues of somatostatins and two CC-chemokines MIP-1alpha and MIP-1beta. The thiaproline replacements in these peptides and proteins did not result in altered biological activity. By eliminating the protecting group scheme and coupling reagents, tandem ligation of multiple free peptide segments in aqueous solutions enhances the scope of protein synthesis and may provide a useful approach for preparing protein biologicals and synthetic vaccines.

Design of salt-insensitive glycine-rich antimicrobial peptides with cyclic tricystine structures

Cyclic peptide backbone and cystine constraints were used to develop a broadly active salt-insensitive antimicrobial peptide [Gly(6)]ccTP 1a with eight Gly residues in an 18-residue sequence. The importance of rigidity and amphipathicity imparted by the cyclic and cystine constraints was examined in two peptide series based on tachyplesin, a known beta-stranded antimicrobial peptide. The first series, which retained the charge and hydrophobic amino acids of tachyplesin, but contained zero to four covalent constraints, included a cyclic tricystine tachyplesin (ccTP 1). Corresponding [Gly(6)] analogues were prepared in a parallel series with all six bulky hydrophobic amino acids in their sequences replaced with Gly. Circular dichroism measurements showed that ccTP 1 and [Gly(6)]ccTP 1a exhibited well-ordered beta-sheet structures, while the less constrained [Gly(6)] analogues were disordered. Except for linear peptides assayed under high-salt conditions, peptides with increased or decreased conformational constraints retained broad activity spectra with small variations in potency of 2-10-fold compared to that of tachyplesin. In contrast, Gly replacement analogues resulted in large variations in activity spectra and significant decreases in potency that roughly correlated with the decreases in conformational constraints. Except against Escherichia coli, the Gly-rich analogues with two or fewer covalent constraints were largely inactive under high-salt conditions. Remarkably, the most constrained [Gly(6)]ccTP 1a retained a broad activity spectrum against all 10 test microbes in both low- and high-salt assays. Collectively, our results show that [Gly(6)]ccTP 1acould serve as a template for further analogue study to improve potency and specificity through single or multiple replacements of hydrophobic or unnatural amino acids.

Activation barriers to structural transition determine deposition rates of Alzheimer's disease a beta amyloid

Brain amyloid composed of the approximately 40-amino-acid human beta-amyloid peptide A beta is integral to Alzheimer's disease pathology. To probe the importance of a conformational transition in Abeta during amyloid growth, we synthesized and examined the solution conformation and amyloid deposition activity of A beta congeners designed to have similar solution structures but to vary substantially in their barriers to conformational transition. Although all these peptides adopt similar solution conformations, a covalently restricted Abeta congener designed to have a very high barrier to conformational rearrangement was inactive, while a peptide designed to have a reduced barrier to conformational transition displayed an enhanced deposition rate relative to wild-type A beta. The hyperactive peptide, which is linked to a heritable A beta amyloidosis characterized by massive amyloid deposition at an early age, displayed a reduced activation barrier to deposition consistent with a larger difference in activation entropy than in activation enthalpy relative to wild-type A beta. These results suggest that in Alzheimer's disease, as in the prion diseases, a conformational transition in the depositing peptide is essential for the conversion of soluble monomer to insoluble amyloid, and alterations in the activation barrier to this transition affect amyloidogenicity and directly contribute to human disease.

Marked increase in membranolytic selectivity of novel cyclic tachyplesins constrained with an antiparallel two-beta strand cystine knot framework

We have developed a highly constrained 18-residue cyclic peptide template based on the antimicrobial peptide tachyplesin-1 that features an end-to-end peptide backbone and a cystine knot-like motif with three evenly spaced disulfide bonds to cross-brace the antiparallel beta-strands and to approximate an amphiphatic "beta-tile"-like structure. Six beta-tile analogs were prepared to correlate different topological patterns with membranolytic specificity. Their conformations and antimicrobial and hemolytic activities were compared with tachyplesin-1 and the recently discovered Rhesus monkey theta defensin (RTD) which contains similar beta-tile structural elements. The beta-tile peptides and RTD retained broad spectrum antimicrobial activities. In general, they were less active than tachyplesin-1 in 10 tested organisms but their activity increased under high-salt (100 mM NaCl) rather than in low-salt conditions. The beta-tile peptides are highly nontoxic to human erythrocytes with EC(25) ranging from 600 to 4000 microM. Collectively, our results show that the design of a highly rigid peptide template is useful for further analog study to dissociate antimicrobial activity from cytotoxicity which would be helpful in discovering clinical applications for peptide antibiotics.

An unusual structural motif of antimicrobial peptides containing end-to-end macrocycle and cystine-knot disulfides

Four macrocyclic cystine-knot peptides of 29-31 residues, kalata, circulin A and B (CirA and CirB), and cyclopsychotride, have been isolated from coffee plants but have undetermined physiological functions. These macrocycles and 10 of their analogs prepared by chemical synthesis were tested against nine strains of microbes. Kalata and CirA were specific for the Gram-positive Staphylococcus aureus with a minimum inhibition concentration of approximately 0.2 microM. They were relatively ineffective against Gram-negative bacteria such as Escherichia coli and Pseudomonas aeruginosa. However, CirB and cyclopsychotride were active against both Gram-positive and Gram-negative bacteria. In particular, CirB showed potent activity against E. coli with a minimum inhibitory concentration of 0.41 microM. All four cyclic peptides were moderately active against two strains of fungi, Candida kefyr and Candida tropicalis, but were inactive against Candida albicans. These macrocycles are cytotoxic and lysed human red blood cell with a lethal dose 50% of 400 microM. Modifying the Arg residue in kalata with a keto aldehyde significantly reduced its activity against S. aureus whereas blocking the arg in CirA produced no significant effect. The two-disulfide variants and their scrambled disulfide isomers exhibited antimicrobial profiles and potency similar to their native peptides. However, in high-salt assays (100 mM NaCl), few of these macrocyclic peptides, natives or analogs, retained antimicrobial activity. These results show that the macrocyclic peptides possess specific and potent antimicrobial activity that is salt-dependent and that their initial interactions with the microbial surfaces may be electrostatic, an effect commonly found in defensin antimicrobial peptides. Furthermore, their end-to-end cyclic structure with a cystine-knot motif represents a molecular structure of antimicrobials and may provide a useful template for the design of novel peptide antibiotics.

A biomimetic strategy in the synthesis and fragmentation of cyclic protein

This paper describes a simple biomimetic strategy to prepare small cyclic proteins containing multiple disulfide bonds. Our strategy involves intramolecular acyl transfer reactions to assist both the synthesis and fragmentation of these highly constrained cyclic structures in aqueous solution. To illustrate our strategy, we synthesized the naturally occurring circulin B and cyclopsychotride (CPT), both consisting of 31 amino acid residues tightly packed in a cystine-knot motif with three disulfide bonds and an end-to-end cyclic form. The synthesis of these small cyclic proteins can be achieved by orthogonal ligation of free peptide thioester via the thia zip reaction, which involves a series of reversible thiol-thiolactone exchanges to arrive at an alpha-amino thiolactone, which then undergoes an irreversible, spontaneous ring contraction through an S,N-acyl migration to form the cyclic protein. A two-step disulfide formation strategy is employed for obtaining the desired disulfide-paired products. Partial acid hydrolysis through intramolecular acyl transfer of X-Ser, X-Thr, Asp-X, and Glu-X sequences is used to obtain the assignment of the circulins disulfide bond connectives. Both synthetic circulin B and CPT are identical to the natural products and, thus, the total synthesis confirms the disulfide connectivity of circulin B and CPT contain a cystine-knot motif of 1-4, 2-5, and 3-6. In general, our strategy, based on the convergence of chemical proteolysis and aminolysis of peptide bonds through acyl transfer, is biomimetic and provides a useful approach for the synthesis and characterization of large end-to-end cyclic peptides and small proteins.

A beta deposition inhibitor screen using synthetic amyloid

The formation, growth, and maturation of brain amyloid "senile" plaques are essential pathological processes in Alzheimer's disease (AD) and key targets for therapeutic intervention. The process of in vitro deposition of A beta at physiological concentrations onto plaques in AD brain preparations has been well characterized, but is cumbersome for drug discovery. We describe here a high-through put screen for inhibitors of A beta deposition onto a synthetic template (synthaloid) of fibrillar A beta immobilized in a polymer matrix. Synthaloid is indistinguishable from plaques in AD brain (the natural template) in deposition kinetics, pH profile, and structure-activity relationships for both A beta analogs and inhibitors. Synthaloid, in contrast to current A beta aggregation screens, accurately predicted inhibitor potency for A beta deposition onto AD cortex preparations, validating its use in searching for agents that can slow the progression of AD and exposing a previously inaccessible target for drug discovery.

Restoration of the transcription activation function to mutant p53 in human cancer cells

The p53 tumor suppressor gene product is a sequence-specific transcription activator frequently mutated in a variety of human malignancies. Typically, tumor-derived p53 missense mutants are defective in DNA binding and this is likely to result in a failure to active p53-regulated genes. Hence, restoring function to mutant p53 represents an attractive target to develop a novel cancer chemotherapeutic agent. We now show that a small chemically modified peptide derived from p53 restores sequence-specific DNA binding to a subset of p53 mutants. Moreover, when microinjected into human colon carcinoma cells this peptide restores the transcription activation function to endogenous mutant p53 protein. This is the first example showing that a small peptide molecule can reverse the effect of several inactivating missense mutations and restore protein function.

Point substitution in the central hydrophobic cluster of a human beta-amyloid congener disrupts peptide folding and abolishes plaque competence

Alzheimer's disease (AD) is pathologically characterized by the presence of numerous insoluble amyloid plaques in the brain composed primarily of a 40-43 amino acid peptide, the human beta-amyloid peptide (A beta). The process of A beta deposition can be modeled in vitro by deposition of physiological concentrations of radiolabeled A beta onto preexisting amyloid in preparations of unfixed AD cerebral cortex. Using this model system, it has been shown that A beta deposition is biochemically distinct from A beta aggregation and occurs readily at physiological A beta concentrations, but which regions and conformations of A beta are essential to A beta deposition is poorly understood. We report here that an active congener, A beta (10-35)-NH2, displays time dependence, pH-activity profile, and kinetic order of deposition similar to A beta (1-40), and is sufficiently soluble for NMR spectroscopy in water under conditions where it actively deposits. To examine the importance of the central hydrophobic cluster of A beta (LVFFA, residues 17-21) for in vitro A beta deposition, an A beta (10-35)-NH2 analog with a single point substitution (F19T) in this region was synthesized and examined. Unlike A beta (10-35)-NH2, the F19T analog was plaque growth incompetent, and NMR analysis indicated that the mutant peptide was significantly less folded than wild-type A beta. These results support previous studies suggesting that the plaque competence of A beta correlates with peptide folding. Since compounds that alter A beta folding may reduce amyloid deposition, the central hydrophobic cluster of A beta will be a tempting target for structure-based drug design when high-resolution structural information becomes available.

Peptide synthesis using unprotected peptides through orthogonal coupling methods

We describe an approach to the synthesis of peptides from segments bearing no protecting groups through an orthogonal coupling method to capture the acyl segment as a thioester that then undergoes an intramolecular acyl transfer to the amine component with formation of a peptide bond. Two orthogonal coupling methods to give the covalent ester intermediate were achieved by either a thiol-thioester exchange mediated by a trialkylphosphine and an alkylthiol or a thioesterification by C alpha-thiocarboxylic acid reacting with a beta-bromo amino acid. With this approach, unprotected segments ranging from 4 to 37 residues were coupled to aqueous solution to give free peptides up to 54 residues long with high efficiency.

Pegylated peptides. IV. Enhanced biological activity of site-directed pegylated GRF analogs

Conditions have been developed for the site-specific pegylation (NH2-terminus, side-chain and carboxy-terminus) of a potent analog of growth hormone-releasing factor, [Ala15]-hGRF(1-29)-NH2. These pegylated peptides were prepared by solid-phase peptide synthesis using the Fmoc/tBu strategy, and were fully characterized by analytical HPLC, amino-acid analysis, 1H-NMR spectroscopy and laser desorption mass spectrometry. Biological activities of hGRF analogs were determined in vitro utilizing stimulation of growth hormone release by cultured rat pituitary cells as an index. GH-releasing potencies of the pegylated hGRF analogs were compared to a series of model analogs of [Ala15]-hGRF(1-29)-NH2 that were acetylated or protected as the ethylamides at the pegylation sites. It was found that acetylation at the NH2-terminus resulted in reduced potency, which was not further affected when the NH2-terminus was pegylated, regardless of the size of poly(ethyleneglycol) (PEG) employed (e.g. PEG2000 or PEG5000). Pegylation at Asp8 or Lys12 decreased biological potency, a situation which was exacerbated by increasing the molecular weight of PEG. Pegylation at Lys21 or Asp25 did not significantly affect biological activity. The C-terminal model peptide, [Ala15,Orn(Ac)30]-hGRF(1-29)-NH2, was the most potent analog identified in this series (ca. 4-5-fold that of hGRF(1-44)-NH2. The COOH-terminal pegylated analogs retained this increased level of biological activity independent of PEG molecular weight. These studies demonstrate that a biologically active peptide can be pegylated and retain the full in vitro potency of the peptide. However, the biological activity is highly dependent on the site of pegylation and, in some cases, the molecular weight of PEG (degree of pegylation) moiety used.

1H NMR of A beta amyloid peptide congeners in water solution. Conformational changes correlate with plaque competence

To begin to examine the structural basis for the deposition of soluble A beta amyloid peptide onto senile plaques in Alzheimer's disease, we have prepared A beta congeners and measured their activity in an in vitro plaque growth assay. The N-terminal fragment, A beta (1-28)-OH, was inactive at all pH values tested. While the central fragment, A beta (10-35)-NH2, and the full length peptide, A beta (1-40)-OH, were inactive below pH 4, both were active (plaque competent) between pH 5 and 9. The active and inactive fragments were studied by nuclear magnetic resonance spectroscopy in water at submillimolar concentrations at pH 2.1 and 5.6. Changes in chemical shifts, coupling constants, and nuclear Overhauser enhancements indicate a pH dependent folding transition in A beta (10-35)-NH2 as it becomes active. The conformation of the active fragment is not helical, and preliminary data indicate the presence of several turns and at least two short strands. In contrast, the inactive fragment A beta (1-28)-OH did not undergo a similar folding transition. Earlier nuclear magnetic resonance studies of amyloid peptides in fluorinated alcohols or detergent micelles at low pH described a helical conformation and proposed a helix to sheet transition in plaque formation; the present study demonstrates that no such conformations are present in water under conditions where the peptides can adhere to authentic amyloid plaques.

Immunization with synthetic peptide segments of a sperm protein impair fertility in rats

The nucleotide sequence of the cDNA encoding a sperm protein (rSMP-B) was determined in a previous study. Two peptide segments corresponding to the extracellular domain of the deduced sperm polypeptide were synthesized as multiple antigen peptide (MAP) and designated as rSMP-229 and rSMP-230. Polyclonal antibodies were raised against the two MAPs. Sera obtained from rabbits immunized with rSMP-230 interacted with human and rabbit sperm membrane proteins with estimated molecular sizes of 72 and 20.1 kD, respectively. Adult female and male rats were immunized with the MAPs and their fertilities determined. Immunization of female rats with rSMP-229 and rSMP-230 induced infertility in 25% and 83% of the treated animals, respectively. All male rats immunized with rSMP-229 remained fertile; whereas animals immunized with rSMP-230 did not mate with normal cycling female rats. Three impotent male rats were found to regain their mating potency 45 days after the last booster injection. These findings demonstrated that immunization with rSMP-230 induced a reversible impotency in male rats. Serum testosterone and LH levels were reduced in rSMP-230-immunized male rats and were elevated in rSMP-229-immunized animals. Histopathological examination of sections of testes from male rats immunized with rSMP-230 showed impairment of spermatogenesis and sloughing of germ cells into the lumen of the seminiferous tubules. The testes of male rats immunized with rSMP-229 showed normal morphology and active spermatogenesis with scattered foci of nodular hyperplasia of Leydig cells in the interstitial areas. In conclusion, immunization with synthetic peptide segments corresponding to different domains of a deduced sperm protein induced infertility in a significant number of female rats and transient impotency in male rats.

Pegylated peptides. II. Solid-phase synthesis of amino-, carboxy- and side-chain pegylated peptides

General procedures are presented for the site-specific pegylation of peptides at the NH2-terminus, side-chain positions (Lys or Asp/Glu) or COOH-terminus using solid-phase Fmoc/tBu methodologies. A model tridecapeptide fragment of interleukin-2, IL-2(44-56)-NH2, was chosen for this study since it possesses several trifunctional amino acids which serve as potential sites for pegylation. The pegylation reagents were designed to contain either Nle or Orn, which served as diagnostic amino acids for confirming the presence of 1 PEG unit per mole of peptide. NH2-Terminal pegylation was carried out by coupling PEG-CH2CO-Nle-OH to the free NH2-terminus of the peptide-resin. Side-chain pegylation of Lys or Asp was achieved by one of two pathways. Direct side-chain pegylation was accomplished by coupling with Fmoc-Lys(PEG-CH2CO-Nle)-OH or Fmoc-Asp(Nle-NH-CH2CH2-PEG)-OH, followed by solid-phase assemblage of the pegylated peptide-resin and TFA cleavage. Alternatively, allylic protective groups were introduced via Fmoc-Lys(Alloc)-OH or Fmoc-Asp(O-Allyl)-OH, and selectively removed by palladium-catalyzed deprotection after assemblage of the peptide-resin. Solid-phase pegylation of the side-chain of Lys or Asp was then carried out in the final stage with PEG-CH2CO-Nle-OH or H-Nle-NH-(CH2)2-PEG, respectively. COOH-Terminal pegylation was achieved through the initial attachment of Fmoc-Orn(PEG-CH2CO)-OH to the solid support, followed by solid-phase peptide synthesis using the Fmoc/tBu strategy. The pegylated peptides were purified by dialysis and preparative HPLC and were fully characterized by analytical HPLC, amino acid analysis, 1H-NMR spectroscopy and laser desorption mass spectrometry.

Pegylated peptides I: Solid-phase synthesis of N alpha-pegylated peptides using Fmoc strategy

The feasibility of pegylating peptides by the solid-phase procedure was examined. Although polyethyleneglycol (PEG) was shown to be partially degraded by HF, the use of TFA was fully compatible with the PEG system. Therefore, the Fmoc/tBu solid-phase strategy was utilized for the synthesis of a series of model tetra-, octa- and dodecapeptides, and the corresponding N alpha-pegylated peptides, which were prepared from common peptide-resin intermediates. PEG-OCH2-CO-Nle-OH, 3, proved to be an ideal reagent for N-terminal pegylation. This intermediate served as a diagnostic for the determination of the number of PEG units/mole of peptide. Solid-phase coupling reactions proceeded by standard procedures using BOP-activation. The authentic pegylated peptides (readily purified by conventional methods of preparative HPLC) were fully characterized by amino acid analysis, 1H-NMR spectroscopy, analytical HPLC and laser desorption ionization mass spectrometry, leading to the values that are identical with the expected structures.

Immunogenicity of multiple antigen peptides containing B and non-repeat T cell epitopes of the circumsporozoite protein of Plasmodium falciparum

We have characterized the immune response of mice to multiple Ag peptide systems (MAP) containing the immunodominant B cell epitope (NANP)3 and one of three distinct Th epitopes, Th2R, Th3R, and CS.T3, of the C terminal region of the circumsporozoite protein of Plasmodium falciparum, a human malaria parasite. Mice of three different MHC haplotypes (H-2k, H-2d, and H-2a) were immunized with the various MAP constructs. Mice of all three strains produced antibodies, but their anti-sporozoite titers were considerably lower than their anti-peptide titers as detected by ELISA. These antibodies reacted at high titers not only with the repeat polymer (NANP)50, but also with MAP that contained only the respective Th sequence. The antibody binding site within each of the Th sequences was mapped, using truncated peptides, in an inhibition assay. A primary antibody response, induced by a single i.v. inoculation of sporozoites, was greatly enhanced by the injection of MAP.

Immunogenicity of multiple antigen peptides containing B and non-repeat T cell epitopes of the circumsporozoite protein of Plasmodium falciparum

We have characterized the immune response of mice to multiple Ag peptide systems (MAP) containing the immunodominant B cell epitope (NANP)3 and one of three distinct Th epitopes, Th2R, Th3R, and CS.T3, of the C terminal region of the circumsporozoite protein of Plasmodium falciparum, a human malaria parasite. Mice of three different MHC haplotypes (H-2k, H-2d, and H-2a) were immunized with the various MAP constructs. Mice of all three strains produced antibodies, but their anti-sporozoite titers were considerably lower than their anti-peptide titers as detected by ELISA. These antibodies reacted at high titers not only with the repeat polymer (NANP)50, but also with MAP that contained only the respective Th sequence. The antibody binding site within each of the Th sequences was mapped, using truncated peptides, in an inhibition assay. A primary antibody response, induced by a single i.v. inoculation of sporozoites, was greatly enhanced by the injection of MAP.

Infertility induced in rats by immunization with synthetic peptide segments of a sperm protein

Three peptide segments (YAL-198, YAL-201 and YAL-212) corresponding to the extracellular domain of a human sperm protein designated as YWK-II antigen were synthesized as multiple antigen peptide (MAP). Male and female rats were immunized with the YWK-II-MAPs and fertility determined. In a group of 12 female rats immunized with YAL-198, seven animals were infertile and two animals were subfertile. When immunized with YAL-201 and YAL-212, 4 and 2 animals were infertile, respectively. In a group of 15 males immunized with YAL-198, 2 animals were infertile and 6 were subfertile. Two animals immunized with YAL-201 were subfertile. All control male and female rats immunized with bovine serum albumin and adjuvant were fertile. Sera obtained from infertile rats immunized with YAL-198 contained higher titers of antibodies compared to those obtained from fertile animals. The present study shows that immunization with synthetic peptide segments of a sperm protein can effectively reduce fertility.

A chemically defined synthetic vaccine model for HIV-1

Multiple Ag peptide (MAP) system without the use of a protein carrier was used as a vaccine model in three species of animals. Synthetic peptides from the V3 region of the gp120 of IIIB, RF and MN HIV-1 isolates were used as the Ag. MAP consisting of various chain lengths, from 11 to 24 residues, were prepared in a monoepitope configuration containing four repeats of each individual peptide. In parallel, they were synthesized in a diepitope configuration adding at the carboxyl-terminus of the V3 peptides a conserved sequence, known to be a Th cell epitope of gp120. The antibody response elicited by the monoepitope constructs was species-dependent. Rabbits produced immunity against all nine peptides, whereas mice were strongly reactive mainly to the longest sequence of the IIIB isolate. The immune response of guinea pigs was intermediate to those of rabbits and mice. Diepitope MAPs were immunogenic in all three species and elicited significantly higher titers than those raised by the immunization with the monoepitope MAPs. The response was type specific; the high-titered antibodies were reactive mostly against the isolate from which the peptides were derived, with a small cross-reactivity in ELISA between IIIB and RF strains. The dominant antigenic site of the B cell epitope, IIIB sequence, was located at the amino and central part of the MAP and a sequence overlapping the putative V3 reverse-turn was particularly reactive with the raised antibodies. Moreover, sera from the immunized animals inhibited virus-dependent cell fusion. These results show that MAP, with a chemically defined structure and without the use of a protein carrier, can be potentially useful for the design of synthetic HIV-1 vaccine candidates.

A chemically defined synthetic vaccine model for HIV-1

Multiple Ag peptide (MAP) system without the use of a protein carrier was used as a vaccine model in three species of animals. Synthetic peptides from the V3 region of the gp120 of IIIB, RF and MN HIV-1 isolates were used as the Ag. MAP consisting of various chain lengths, from 11 to 24 residues, were prepared in a monoepitope configuration containing four repeats of each individual peptide. In parallel, they were synthesized in a diepitope configuration adding at the carboxyl-terminus of the V3 peptides a conserved sequence, known to be a Th cell epitope of gp120. The antibody response elicited by the monoepitope constructs was species-dependent. Rabbits produced immunity against all nine peptides, whereas mice were strongly reactive mainly to the longest sequence of the IIIB isolate. The immune response of guinea pigs was intermediate to those of rabbits and mice. Diepitope MAPs were immunogenic in all three species and elicited significantly higher titers than those raised by the immunization with the monoepitope MAPs. The response was type specific; the high-titered antibodies were reactive mostly against the isolate from which the peptides were derived, with a small cross-reactivity in ELISA between IIIB and RF strains. The dominant antigenic site of the B cell epitope, IIIB sequence, was located at the amino and central part of the MAP and a sequence overlapping the putative V3 reverse-turn was particularly reactive with the raised antibodies. Moreover, sera from the immunized animals inhibited virus-dependent cell fusion. These results show that MAP, with a chemically defined structure and without the use of a protein carrier, can be potentially useful for the design of synthetic HIV-1 vaccine candidates.

Immunological evaluation of the multiple antigen peptide (MAP) system using the major immunogenic site of foot-and-mouth disease virus

The multiple antigenic peptide (MAP) system for presenting epitopes to the immune system has been studied with an immunogenic foot-and-mouth disease virus (FMDV) peptide comprising amino acids 141-160 of protein VP1. Neutralizing antibody responses known to protect guinea-pigs against challenge infection were obtained with a single inoculation of 0.8-4 micrograms of peptide, presented as an octamer or a tetramer, whereas 20 micrograms of a dimer were required to evoke a similar level of antibody. A monomeric preparation did not elicit measurable levels of neutralizing antibody at doses up to 20 micrograms. The octameric MAP was also immunogenic using an aluminum hydroxide adjuvant. Antibodies elicited by the octameric, tetrameric and dimeric constructs differed qualitatively in their reaction with sequences within the 141-160 peptide. Those against the octamer reacted poorly with peptides within the 141-160 sequence, whereas those elicited by the tetramer and dimer reacted preferentially with the peptides covering the N-terminal region. The levels of neutralizing antibody obtained with the octamer and tetramer compare favourably with those obtained when the FMDV peptide is attached to carrier proteins but are lower than those obtained when it is presented as part of a peptide-hepatitis B virus core particle. Nevertheless, the ability to elicit protective levels of neutralizing antibody without the use of a carrier protein would be a distinct advantage in the development of synthetic peptide vaccines.

Chemically unambiguous peptide immunogen: preparation, orientation and antigenicity of purified peptide conjugated to the multiple antigen peptide system

We described a novel and simple approach to prepare chemically unambiguous peptide immunogen using the multiple antigen peptide (MAP) approach. This approach requires the conjugation of two purified components: a chloroacetylated oligomeric lysine core matrix and a synthetic peptide containing cysteine at either the carboxyl or amino terminus. The resulting MAP is structurally unambiguous and contains a quantifiable amount of peptide antigens. Furthermore, this method also provides a flexible strategy to link a peptide antigen to the core matrix at the desirable orientation to mimic the native molecule. The carboxyl fragment 43-50 of human transforming growth factor alpha (TGF alpha) was used as a test model for this approach. Antipeptide antibodies did not recognize the "reverse immunogen" in which the peptide was attached to the MAP core matrix at a reverse orientation. To determine the specificity of the antibodies, we used two series of point-substituted TGF alpha analogs containing either alanine or the corresponding D-amino acid replacement to map the antigenic site. The alanine analogs were used to determine the contribution of the side chain while the D-amino acid analogs were used to determine the importance of backbone conformation. The antigen site was found to consist of four residues (Asp47-Leu48-Leu49-Ala50) at the distal end of the peptide-MAP conjugate. The results provide a clear explanation for the specificity of the antipeptide antibodies and their failure to recognize the "reverse immunogen" since the distal and the flexible end of the peptide-MAP construct constitutes the antigenic site. Furthermore, our results also suggests a strategy of placing the antigenic portion of a short-peptide at the distal end in the MAP approach to prepare immunogen.

A new virus isolate from infectious hypodermal and hematopoietic necrosis virus (IHHNV)-infected penaeid shrimps

A new virus was isolated from infectious hypodermal and hematopoietic necrosis virus (IHHNV)-infected penaeid shrimps. The virus was isolated from two species of penaeid shrimps obtained from three different sources employing a previously developed cell-culture assay. Electron-microscopical studies of both purified virus and infected cells showed bullet-shaped particles identifying it as a rhabdovirus.

Fish cell lines: establishment and characterization of three new cell lines from grass carp (Ctenopharyngodon idella)

Three new cell lines were established from tissues of the grass carp, Ctenopharyngodon idella. Derived from the fin, snout, and swim bladder of two apparently healthy diploid fry, these cell lines have been designated GCF, GCS-2, and GCSB, respectively. The cells grew at temperatures between 24 degrees and 36 degrees C with optimal growth at 32 degrees C and have been subcultured more than 50 times since their initiation in August 1986. Two of the lines remained diploid or pseudodiploid after 38 passages. The cells were tested for microbial contamination, and plating efficiencies were determined. The three cell lines were sensitive to Rhabdovirus carpio (RVC), infectious hematopoietic necrosis virus (IHNV), golden shiner virus (GSV), chum salmon virus (CSV), and infectious pancreatic necrosis virus serotype VR299 IPNV). They were refractory to channel catfish virus (CCV), channel catfish reovirus (CRV), chinook salmon paramyxovirus (CSP), and an Ab serotype of IPNV.

Incorporation of T and B epitopes of the circumsporozoite protein in a chemically defined synthetic vaccine against malaria

We show here an effective and novel approach to engineer peptide-based vaccines using a chemically defined system, known as multiple peptide antigen systems (MAPs), to protect an inbred mouse strain from infection against rodent malaria. 10 mono- and di-epitope MAP models containing different arrangements and stoichiometry of functional B and/or T helper cell epitopes from the circumsporozoite protein of Plasmodium berghei were used to immunize A/J mice. While these mice did not respond to the mono-epitope MAP bearing only the B or T epitope, very high titers of antibody and protective immunity against sporozoite challenge were elicited by di-epitope MAPs, particularly those with the B and T epitopes in tandem and present in equimolar amounts. These results, obtained in a well-defined rodent malaria model, indicate that MAPs may overcome some of the difficulties in the development of synthetic vaccines, not only for malaria but also for other infectious diseases.

Vaccine engineering: enhancement of immunogenicity of synthetic peptide vaccines related to hepatitis in chemically defined models consisting of T- and B-cell epitopes

We report the development of two models for synthetic hepatitis B vaccines. The models were based on the multiple antigen peptide (MAP) system and contained the relevant B- and T-cell epitopes without any macromolecular carrier. Two peptides, representing the a determinant of the S region (S protein) of hepatitis B surface antigen, a dominant serotype of hepatitis B virus infection found in humans, and residues 12-26 of the pre-S(2) region of the middle protein were incorporated as either monoepitope or diepitope MAP models. Immunizations of outbred rabbits with the monoepitope MAP that contains the pre-S(2) antigen resulted in high-titered antibody response to the middle protein, but the other monoepitope, containing only the a-determinant peptide antigen, resulted in poor immune responses to either the peptide antigens or to the S protein. The diepitope MAPs containing both the a and the pre-S(2) determinants produced high-titer antibodies reactive to the a-synthetic peptide and the S protein, as well as to the middle proteins. Thus, our results show that the diepitope MAP models eliminate the need for a protein carrier and that the pre-S(2) peptide determinant serves as a T-helper cell epitope that enhances the immune response of the S region and overcomes the poor immunogenicity encountered with a single epitope of the S region.

Isolation, amino acid sequence, synthesis, and biological activity of some oligopeptides from porcine spinal cord

Four oligopeptides, designated SCP-3, SCP-4, SCP-5, and SCP-6, have been isolated and purified to homogeneity from porcine spinal cord. The amino acid sequences have been determined as pyroGlu-Gly, pyroGlu-Gly-Gly, Met-Met-Gly, and Asp-Ala-Gly-Ala-Gly, respectively. All of these peptides have been synthesized by conventional liquid-phase or solid-phase methods. The synthetic and extracted peptides showed identical behavior in a reverse-phase high-performance liquid chromatography system. SCP-3 and SCP-4 exhibited some significant inhibitory activity on the electrical stimulation-induced contractions of longitudinal muscle strip of guinea pig ileum, and SCP-5 showed some stimulating effect on the same preparation. The physiological significance of these purified peptides is being investigated.